It is known in the art of railroad track shifting machines, such as track lifting and/or tamping machines, to provide on a rigid frame, an adjustable shift stop which provides a rail engaging surface against which the track "bottoms" during shifting operations, such as a lifting and/or tamping operation, so as to prevent further lifting of the track. After a rail engages the stop, however, the continuation of the jacking or tamping can cause damage to the rail between the stop and the point of shift.